Specific Process Knowledge/Thin film deposition/Deposition of Alumina/E-beam Evaporation of Al2O3 in Temescal-2

This page is written by Evgeniy Shkondin @DTU Nanolab if nothing else is stated.
All images and photos on this page belongs to DTU Nanolab.
The fabrication and characterization described below were conducted in 2023 by Patama Pholprasit and Evgeniy Shkondin, DTU Nanolab.

Evaporation of Al₂O₃ in Temescal-2

This page describes e-beam evaporation method of Al₂O₃ in Temescal (10-pocket). E-Beam Evaporator (10-pockets) - Temescal-2 allows deposition with elevated temperature and O₂ gas bleed. This is ideal conditions of evaporation of oxides such as SiO₂, TiO₂, Al₂O₃ and ITO.

In these tests we evaporated Al₂O₃ with 5% O₂ and with and without temperature of 200 °C. Please be aware that evaporations requiring elevated temperatures should only be conducted using the 8-inch holder (as shown in the photo) with an adaptor tailored to the wafer size. Various accessories enable the use of the 8-inch wafer holder with a range of samples, from 8-inch wafers to small chips. NEVER attempt to use HULA with high-temperature processes, as they can potentially damage the magnetic components of HULA. If you are unsure, please consult the tool responsible for guidance.

Al₂O₃ evaporates from source 9 or 10 in Temescal-2 using a graphite liner. Please write to metal@nanolab.dtu.dk at least a week in advance if you wish to request a material in a liner in pocket 9 or 10. The rise-soak sequence is slightly modified, so soak-1 power is sat higher compared to soak-2 power. This is due to the different sweep patterns implemented during the rise-soak and deposition phases.

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  Photo of the Al₂O₃ in the crucible during the evaporation.

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  Photo of the 8-inch holder installed instead of HULA and used in Al₂O₃ and SiO₂ evaporation tests.

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  Al₂O₃ rise-soak procedure. Deposition rate: 1 Å/s.

Uniformity across 150 mm wafer

Results have been obtained for <100> 150 mm Si wafers with native oxide, based on ellipsometry study.

Temperature (°C) / Thickness setpoint	Deposition rate (nm/s)	Tooling Factor (5)	Gas O2 (%)	Average thickness (nm)	Minimum thickness (nm)	Maximum thickness (nm)	Standard deviation	Uniformity (%)
200°C / 60 nm*	1	58	5	81.95	80.12	83.39	1.0400	1.9965
room temperature / 80 nm	1	85	5	91.52	88.17	93.29	1.5056	2.8001
200°C / 80 nm	1	85	5	85.98	83.02	87.55	1.3718	2.6357

• * Initial test for tooling factor adjustment.

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  Measured and fitted Psi and Delta functions of Al₂O₃ thin film deposited on Si wafer using the e-beam evaporation method.

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  Thickness uniformity of Al₂O₃ deposited on Si wafer using e-beam evaporation with 5% O₂ gas and at 200°C. Thickness setpoint sat to 60 nm.

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  Thickness uniformity of Al₂O₃ deposited on Si wafer using e-beam evaporation with 5% O₂ gas and at 200°C. Thickness setpoint sat to 80 nm.

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  Thickness uniformity of Al₂O₃ deposited on Si wafer using e-beam evaporation with 5% O₂ gas and at room temperature. Thickness setpoint sat to 80 nm.

Optical functions

Results have been obtained for <100> 150 mm Si wafers with native oxide, based on ellipsometry study. Cauchy model has been implemented for refractive index fitting.

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  Refractive index of 80 nm Al₂O₃ deposited on silicon at room temperature and 200°C.

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  Absorption coefficient of 80 nm Al₂O₃ deposited on silicon at room temperature and 200°C.

Deposition recordings

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  Al₂O₃ evaporation monitoring. Deposition rate recording. Temperature 200°C, 5% O2, thickness setpoint 60 nm.

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  Al₂O₃ evaporation monitoring. Gas flow recording. Temperature 200°C, 5% O2, thickness setpoint 60 nm.

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  Al₂O₃ evaporation monitoring. Power recording. Temperature 200°C, 5% O2, thickness setpoint 60 nm.

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  Al₂O₃ evaporation monitoring. Pressure recording. Temperature 200°C, 5% O2, thickness setpoint 60 nm.

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  Al₂O₃ evaporation monitoring. Temperature recording. Temperature 200°C, 5% O2, thickness setpoint 60 nm.

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  Al₂O₃ evaporation monitoring. Deposition rate recording. Room Temperature, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Gas flow recording. Room Temperature, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Power recording. Room Temperature, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Pressure recording. Room Temperature, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Temperature recording. Room Temperature, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Deposition rate recording. Temperature 200°C, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Gas flow recording. Temperature 200°C, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Power recording. Temperature 200°C, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Pressure recording. Temperature 200°C, 5% O2, thickness setpoint 80 nm.

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  Al₂O₃ evaporation monitoring. Temperature recording. Temperature 200°C, 5% O2, thickness setpoint 80 nm.